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authorJeff Moyer <jmoyer@redhat.com>2011-11-02 13:40:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-11-02 16:07:03 -0700
commit080d676de095a14ecba14c0b9a91acb5bbb634df (patch)
tree4a4c56bc86a8edf4a42f8ec7c65ba795997e50ab /include/linux/aio.h
parent2ca02df6b098be2d33a99a65531dcd84a10b6e21 (diff)
aio: allocate kiocbs in batches
In testing aio on a fast storage device, I found that the context lock takes up a fair amount of cpu time in the I/O submission path. The reason is that we take it for every I/O submitted (see __aio_get_req). Since we know how many I/Os are passed to io_submit, we can preallocate the kiocbs in batches, reducing the number of times we take and release the lock. In my testing, I was able to reduce the amount of time spent in _raw_spin_lock_irq by .56% (average of 3 runs). The command I used to test this was: aio-stress -O -o 2 -o 3 -r 8 -d 128 -b 32 -i 32 -s 16384 <dev> I also tested the patch with various numbers of events passed to io_submit, and I ran the xfstests aio group of tests to ensure I didn't break anything. Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Cc: Daniel Ehrenberg <dehrenberg@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/aio.h')
-rw-r--r--include/linux/aio.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/aio.h b/include/linux/aio.h
index 2dcb72bff4b..2314ad8b3c9 100644
--- a/include/linux/aio.h
+++ b/include/linux/aio.h
@@ -117,6 +117,7 @@ struct kiocb {
struct list_head ki_list; /* the aio core uses this
* for cancellation */
+ struct list_head ki_batch; /* batch allocation */
/*
* If the aio_resfd field of the userspace iocb is not zero,